A heavy winter storm that slammed the US southeast and made its way up to the north has left over a dozen people dead and knocked out electricity to hundreds of thousands of American homes.

The giant storm, called “Snowmaggedon”, has also caused massive traffic jams on roads. Meanwhile, air travelers are also confused as hundreds of flights have been called off.

Most outbound flights from Newark, New Jersey, were canceled Thursday. Almost half of the inbound flights were also canceled, according to the flight-tracking website FlighAware.com.

As of Thursday 8 a.m., more than 4,800 flights were canceled across the US, according to the website.

Weather experts say some US cities can expect more than 30 centimeters of snow by the end of Thursday as the storm is moving up the East Coast.

The storm has also led to cancelations of 44 percent of the New York City’s LaGuardia outbound flights and 37 percent of the inbound flights.

Kennedy airport in New York City also saw about one-fifth of the day’s routes canceled by Thursday morning.

The storm and heavy snow also crippled road travel and knocked out power to nearly 400,000 homes and businesses in the region, where at least 13 people were killed because of the icy weather, Reuters reported.

According to meteorologists, an accumulation of ice and heavy snow is expected to add up to nearly 8 inches of frozen precipitation for Charlotte, North Carolina, and 9 inches were forecast for Spartanburg, South Carolina.